In the vector coding technology, residual signals subsequent adaptive filtering generally undergo quantization coding using algebraic codebooks. After the information about the position and the sign of the optimum algebraic codebook pulse on the track is searched out, the corresponding index value is calculated out through coding such that the decoder can reconstruct a pulse order according to the index value. One of the main objectives of researching and developing the algebraic codebook pulse coding method is to minimize the bits required by the coding index value on the precondition of ensuring lossless reconstruction.
The extended adaptive multi-rate wideband (AMR_WB+) coding method is an algebraic codebook pulse coding method in the conventional art. Depending on the coding rate, one to N pulses may be encoded on each track. With the increase of coding pulses, the bits required for encoding such an amount of pulses also increase. For example, for a track with M=2m positions, encoding one pulse on the track requires m+1 bits, and encoding six pulses on the track requires 6 m-2 bits. In the process of developing the present disclosure, the inventor finds that in the algebraic pulse coding in the conventional art, a recursion-like coding method is applied to break down a coding pulse with many pulses into several coding pulses with fewer pulses, thus making the coding process rather complex. Meanwhile, with the increase of coding pulses on the track, the redundancy of the coding index accrues, thus tending to cause waste of coding bits.